http://www.beadalon.com/BeadBoards.asp

Standard jewelry lengths are:
Choker: 15-16"
Princess necklace: 18-20"
Matinee necklace: 23-27"
Bracelet: 7"
Anklet: 9-10"

Use a bead board to help you determine the length of a design as you’re beading. A bead board also lets you see what a design will look like before you string it. That way you don't have to re-string the entire design if you find out that you don't have enough beads to complete the pattern you have in mind.

Use the measurements on the outside of the bead board to determine (in inches) how the long a design in the outer channel will be. The numbers along the inside indicate the length of a design in the inner channel in centimeters. For example, a pattern that reaches 7 1/2 on both sides in the outer channel would make a 15" necklace. Once you add a 1” clasp, the necklace will be 16” long, which is standard length for a choker.

For more ideas and inspiration visit: www.katiehacker.com